US4361643A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photomask and method of using same
Assignee: AT&T Inc
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Filing: 1981-07-29
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Granted: 1982-11-30
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Expires: 2001-07-29
Abstract
Abstract A photomask (30) used to form patterns on a resist coated semiconductor wafer is comprised of a transparent baseplate (31) having a thin metallic pattern (32) thereon; a transparent, planar coverplate (33) in intimate contact with the patterned baseplate (31) and an index matching fluid (34) interposed therebetween.
Inventors
- 👤 Edward L. Banks
- 👤 Bruce E. Truax
- 👤 Laurence S. Watkins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 21:53
CPC Classifications
G; G03; G03F; G03F1/00; G03F1/38; G03F1/48; Y; Y10; Y10T; Y10T428/00; Y10T428/24; Y10T428/24802; Y10T428/24851; Y10T428/24868; Y10T428/24917; Y10T428/24926; Y10T428/31
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
50 words
A photomask, comprising: a light transmissive baseplate having a metallic pattern thereon; a light transmissive coverplate having opposed, substantially parallel major surfaces, in intimate contact with the patterned baseplate; and a refractive index matching fluid interposed between, and having substantially the same refractive index as, the baseplate and the coverplate.
Claim 2
Dependent Claim
50 words
A photomask, comprising: a light transmissive baseplate having a metallic pattern thereon; a light transmissive coverplate having opposed, substantially parallel major surfaces, in intimate contact with the patterned baseplate; and a refractive index matching fluid interposed between, and having substantially the same refractive index as, the baseplate and the coverplate.
Claim 3
Dependent Claim
40 words
The photomask as set forth in claim 1, wherein: the surface of the coverplate is flat to at least 4 μm; and the opposed major surfaces of the cover plate are parallel to each other at least 4 82 m.
Claim 4
Dependent Claim
28 words
The photomask as set forth in claim 1, characterized by: a seal at the interface edge between the coverplate and baseplate to maintain the index matching material therebetween.
Claim 5
Independent Claim
93 words
A method of selectively exposing a photoresist coated substrate to light radiation, comprising the steps of: positioning a photomask between a light source and the photoresist coated substrate, the photomask comprising: (a) a light transmissive baseplate having a metallic pattern thereon; (b) a light transmissive coverplate in intimate contact with the patterned baseplate; (c) a refractive index matching fluid interposed between, and having substantially the refractive index as, the baseplate and the coverplate; and activating the light source to direct light radiation through the photomask to selectively expose the photoresist coated substrate thereto.
Claim 6
Independent Claim
93 words
A method of selectively exposing a photoresist coated substrate to light radiation, comprising the steps of: positioning a photomask between a light source and the photoresist coated substrate, the photomask comprising: (a) a light transmissive baseplate having a metallic pattern thereon; (b) a light transmissive coverplate in intimate contact with the patterned baseplate; (c) a refractive index matching fluid interposed between, and having substantially the refractive index as, the baseplate and the coverplate; and activating the light source to direct light radiation through the photomask to selectively expose the photoresist coated substrate thereto.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-11-29 | 1986-05-31 | 1986-11-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-11-29 | 1990-05-31 | 1990-11-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-11-29 | 1994-05-31 | 1994-11-30 | $7700.00 | Window Closed / Lapsed |